1. What is BMI?

Body Mass Index (BMI) is a person's weight in kilograms divided by the square of height in meters. For children and teens, BMI is age- and sex-specific and is often referred to as BMI-for-age.

2. How Does the Calculator Work?

The calculator uses the standard BMI formula:

For children, the BMI is plotted on CDC growth charts to determine the BMI-for-age percentile:

• Underweight: BMI < 5th percentile
• Healthy weight: 5th to <85th percentile
• Overweight: 85th to <95th percentile
• Obese: ≥95th percentile

3. Importance of BMI Calculation

Details: BMI is a screening tool to identify possible weight problems. For children, BMI is particularly important because it accounts for normal differences in body fat between boys and girls and differences at various ages.

4. Using the Calculator

Tips: Enter weight in kilograms and height in meters. For children, also enter age and gender to estimate the BMI percentile. For adults, the standard BMI categories apply.

5. Frequently Asked Questions (FAQ)

Q1: Why use different charts for children?
A: Children's body composition varies as they grow, so BMI must be interpreted relative to other children of the same age and sex.

Q2: What are the BMI categories for adults?
A: Underweight (<18.5), Normal weight (18.5-24.9), Overweight (25-29.9), Obese (≥30).

Q3: How accurate is BMI?
A: BMI is a screening tool but doesn't directly measure body fat. Athletes may have high BMI due to muscle mass.

Q4: When should I be concerned about my child's BMI?
A: Consult a healthcare provider if your child's BMI is below 5th percentile or at/above 85th percentile.

Q5: Where can I find official CDC growth charts?
A: CDC growth charts are available at https://www.cdc.gov/growthcharts/